Method for over-end winding of yarns

ABSTRACT

A process for producing a yarn package substantially free from ridges comprising winding the yarn into a package by means of a ring and traveller and spindle assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay according to one or more values of at least substantially constant wind ratio calculated to avoid regions of patterning in the package and maintaining the wind ratio programme at least during a part of the winding.

United States Patent {mm mm 0/ 70,0 Taper on Rick/19's) Key et al. June 3, 1975 1 METHOD FOR OVER-END WINDING OF YARNS {561 References Cited [75] Inventors: Kenneth Andrew Key. UNITED STATES PATENTS Abcrgavenn); Clive William 1658,68) ll/l953 Waldrop 242/l8.l Hooper, Newport; both of England 3137.987 6/l964 POIIS .i 324L779 3/1966 Bray ct al 242/l8.l 1 Asslsnsel llflpffrlal Chemwal Industries 3.325.985 6/1967 Bucher 1 57/93 Limited. London, England 3334342 8/1967 Pillar ct al. 242/177 22 Filed: May 30, 1973 i Primary E.\'aminerJohn Petrakes pp 365.196 Attorney. Agent, or FirmCushman, Darby &

Related us. Application Data Cushma [60] Division of Sen No. 884,772 Dec. 23. 1969,

abandoned. which is a continuation of Ser. No. [57] BSTRACT 695736.12111. 4. l968 abandoned A Process for Producmg a y P g substantlany free from ridges comprising winding the yarn into a 30] F i A li i priority Data package by means of a ring and traveller and spindle km 17 1967 Ummd Kingdom 7476/67 assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of 1521 us. (:1. 57/156- 57/55 5- 57/75 the 0f lay according to one more Values of 57/157 5; 242/181. 7 4' s; 5 4 least substantially constant wind ratio calculated to 5 1] Int. Cl n Dolh f avoid regions of patterning in the package and main- Field of Search M 57/92 97 55 5 H6 taining the wind ratio programme at least during 21 57/157 5. 34 R. 157 R; 242/l8.l. 159. 174, of wmdmg' 176, 178 177 5 Claims, 5 Drawing Figures Wind POI/ 0 PATENTED JUNE-s 1975 SHEET 2 N EE 55% i BuQQEQh 6 KMS h 1 METHOD FOR OVER-END WINDING F YARNS This is a division of abandoned application Ser. No. 884,772, filed Dec. 23, 1969, as a continuation of application Ser. No. 695,736, filed Jan. 4, 1968, now abandoned.

The invention concerns improvements in or relating to the over-end winding of yarn, and to packages of yarn so wound.

BACKGROUND OF THE INVENTION Over-end winding of yarn, as on the well-known ring spinning machine, is practiced when it is desired to impart a twist to the yarn by the act of winding.

A common instance of such over-end winding is to be found in the drawtwisting of synthetic polymer filaments; and the present invention will be described in relation to such drawtwisting, although it is to be understood that the invention is not limited thereto.

A drawtwister is essentially a downtwister in which roll mechanisms are incorporated for drawing undrawn yarn. Usually, such mechanisms consist of nip rolls ro tated at a given speed acting as feed rolls; and a draw roll and separator roll combination. the former roll of which is rotated at the required higher speed to effect the drawing action on the filaments in question. From the draw roll, the drawn filaments proceed in a generally downward direction to a thread guide positioned axially, or near-axially, of the spindle ofa ring and traveller ring spinning mechanism. This thread guide is sometimes known as the balloon guide, as the yarn is ballooned beneath it by virtue of the rotation of the traveller around the ring. The filaments are then wound up on a bobbin mounted on the rotating spindle, by passage around the traveller which is itself rotated around the ring and by reciprocation of the ring, in its rail, tray or other carrier, in the axial direction of the spindle according to the builder motion required for the particular yarn package to be wound on the bobbin.

It is a quite usual artifice to tilt the ring of the ring spinning mechanism in order that the filaments shall be laid on to the bobbin and yarn package in helical coils having a wavy path rather than a flat helical one. An angle of tilt of between 3 and 6 is usual; although an angle even as low as 1 may be selected and will donate an appreciable wave component to the laying-on path of the yarn. Rings are not generally set to a greater degree of accuracy than within i /2 of the intended value.

Such ring tilt is at least a major factor predisposing the formation of regions of patterning at certain radii of the package build. owing to the coincidence of adjacent coil loci. The incidence of these various regions of patterning, which patterning is to be avoided both from the technical point of view of package stability and yarn take-off characteristics and from the point of view of appearance, can be calculated, e.g., by analogue computer, for any given process involving a drawtwisting wind-up; and hence it is possible to so programme" the winding conditions that the regions of patterning which normally would occur shall be avoided.

The conditions leading to patterning are related to the wind ratio:" that is, the ratio of the number of revolutions per minute of the point of winding-on the package to the number of revolutions per minute of the traveller; or, expressed in another way, the number of package circumferences in one wave of ring tilt. Patterning will be severe at and around integral values of wind ratio; and consequently the spindle speed programme is devised, according to the above known method, so that the speed is shifted to the alternate one when the winding conditions approach a value of wind ratio, for the primary speed, at which patterning will occur, and is then shifted back to the primary one when similarly patterning is due to be encountered at the alternate speed.

SUMMARY OF THE INVENTION It has now been discovered that a novel, ridge-free, uniform-surfaced yarn package can be wound, even with coils that are laid on the package with the wavy motion produced by tilting of the ring, provided that the yarn is wound at one or more values of at least substantially constant wind ratio falling between those values of wind ratio, such as 1:2 and 1:1, which are known to produce regions of patterning.

The novel, ridge-free, uniform-surfaced yarn package is one wound with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay, and is characterised by the absence of any ridges due to wind ratio patterning which are greater than 4 thousandths of an inch in height, when measured by a 3/32 inch diameter probe of a Talysurf surface-measurement recording instrument operating under not greater than 10 gms. pressure on the stylus. The amount of ring tilt specified is any amount at least as great as the minimum purposeful amount providing some overlapping of adjacent coils.

By ridge-free" we mean that the package surface at any stage in the winding of the full package is free from ridges having adjacent peak to valley heights, as characterised above. Measurement should take place along an axial portion of the package that has not been disturbed, e.g. by previous traverses of the measuring stylus.

The value of 4 thousandths of an inch is not an absolute measure of the height of the ridges, as will be evident from the definition of the relatively large diameter probe employed, this size of probe being chosen so as not readily to disturb the coils of yarn. In fact, however, this manner of measurement has been found to correlate with the visual appearance of the packages under normal conditions of inspection, packages having a maximum ridge height as defined being uniformly smooth in appearance.

Although ridges in the surface of a package more severe than those defined above can be caused by other winding defects than those due to wind ratio patterning, it is possible for the first time, on account of this invention, to wind a package with each coil of yarn having a wavy lay such as to cause it to overlap with the neighbouring coils, which package is ridge-free. Naturally, the merit of the invention will not be fulfilled, completely or partially, if ridges due to any cause are present, which ridges are more severe than those as characterised above. Consequently, the preferred yarn package according to the invention is one which is free from ridges, as defined, due to any cause.

According to one manner of producing the novel yarn package of the invention, the winding conditions of, e.g., a drawtwister for nylon yarn, during at least a part of the winding are programmed according to a pattern-avoiding constant wind ratio, e.g., one derived from an analogue computer plot.

It is possible so to programme the winding conditions by either varying the spindle rotational speed or varying the yarn delivery speed to the wind-up. Since it is usually desirable, although not essential, to maintain the yarn delivery speed constant, the usual manner of programming will be the former.

In view of the fact that the usual winding conditions, including the diameter of the tube on which the yarn is to be wound and the final diameter of the package, are such that the pattern-forming wind ratios of 1:2 and 111 would normally be encountered during the winding of the package, a constant wind ratio is selected, by observation of the analogue computer plot, which will avoid these ratios and those others which are a ratio of small whole numbers either of which is less than 5. Suitable such ratios can be worked out and maintained within i 4%, preferably within i2%, to ensure that no critical patterning regions are encountered. Wind ratios between lzl and 2:1 are the most likely to be productive of sufficiently wide pattern-free regions within which control of constancy of the ratio may be maintained in practice.

The manner in which, for any given yarn and process, the wind ratio or ratios is or are selected is as follows. From the computer plot, certain regions are detectable which can be surmised to provide freedom from interference with pattern-forming regions during the period of the wind, the width of such regions being greater, at,

say 5%, than the limits within which it is feasible to control the wind ratio and within which the criteria for the ridge-free packages are met.

Steps may need to be taken to narrow the patternforming regions, as by reducing the traverse speed or increasing the diameter of the ring, in order to provide the required width of pattern-free region within which to operate.

Then, packages are wound over a range of wind ratios within the detected pattern-free regions to establish empirically just which ratios do meet the criteria for ridge-free packages, packages which look smooth corresponding as a rule with those which pass the Talysurf test.

The appearance of the packages at and around the reversals of traverse is important, due to the effect of traversing on the delivery speed, which effect may be contained to, say, i in terms of wind ratio.

The actual means to be employed for giving effect to the constant wind ratio conditions of winding may take one of several forms. For instance, the spindle drive motor may be programmed direct from an analogue computer or other programme-creating means such as a cam: or, alternatively, certain relevant features of the winding operation, such as the traveller speed of a ring spindle wind-up, may be monitored eg at one position or at all positions and then averaged, and electrical signals derived therefrom may be processed in electronic equipment according to the equations relevant to constant wind ratio (to be referred to below), and an output signal therefrom fed to an error computing circuit into which is also fed a signal representing actual spindle speed.

Any error signal therefrom can be modified by a stabilising circuit and is then capable of controlling the speed of the spindle drive motor in a stable closed loop circuit.

The equation for constant wind ratio which is referred to above is when S Spindle r.p.m.

W= Wind ratio (desired) T Traveller r.p.m.

It will be clear, therefore, if T is monitored, and the proportional electrical signal therefrom is multiplied, e.g., in a simple potentiometer and amplifier combination, by (W l), a continuing value of S can be obtained for the control of the spindle drive motor.

DESCRIPTION OF THE PREFERRED EMBODIMENT Traveller speed, T, can be monitored, for instance, photo-electrically or else by magnetic pick-up. The latter method is preferred owing to the possibility that extraneous light may effect the operation of a photoelectric detector means. According to the magnetic detection method, a metal or metal-containing traveller disturbs the magnetic field of a magnet attached to the ring each time the traveller performs one revolution of the ring. Pulses are thereby produced in an electrical circuit containing a coil, which may also be attached to the ring, and these pulses may then be fed to a ratemeter, the output of which is fed to a potentiometer and amplifier combination for multiplication by the (W 1) factor, and then compared in an error-computing circuit with the actual spindle speed derived from a tachometer or a second detector and rate-meter observing the spindle. The error signal can then be modified by a stabilising circuit so that it may be used to drive the spindle in a stable closed loop.

In the latter instance, since the traveller speed has to be brought up within the working range of the ratemeter before the loop is closed, it is necessary to make arrangements for this initial pre-loop-closing acceleration to be performed, preferably during the winding of the waste bunch of yarn that is customarily wound below the bobbin at start up.

When parallel-sided, double-taper packages are being wound, it may be necessary to avoidthe electronic servo-motor taking correcting action in respect of the adventitious change in traveller speed which may occur at reversals where, due to the tilt of the ring, the yarn may be wound a small way along the tapered endportions. One way of achieving this is simply to cut out the servo-motor just before the reversals until the traverse is moving in the opposite direction.

DRAWINGS The invention will now be illustrated by traces of Talysurf measurements, histograms, and by examples of processes which produce ridge-free uniformsurfaced yarn packages of nylon multi-filament yarn.

The traces and histograms above referred to are shewn in the accompanying drawings, FIGS. 1-5 inclusive, in each of which the traces were taken from the Talysurf recorder measuring over the full axial length of the cylindrical portion of the package, from top to bottom of the same package(bobbin diameter= 1.86 in.) before measurement took place, separate packages having been wound at each of a series of constant wind ratios between values thereof of l.08 and 1.16. The histograms demonstrate the accuracy with which the respective constant wind ratios were maintained.

The packages were re-wound from drawtwist packages of 60 denier/ filament yarn of polyhexamethylene adipamide, the winding conditions being:

18 in. per minute 2.5 g. 2.500 feet per minute.

Constant wind ratio was maintained by means as described above for the preferred embodiment.

In the traces, one small division of the graph is equal to 1 thousandth of an inch (0.001 in). The trace above the zero line represents the recording of the stylus itself; whilst the trace below the zero line shows the peak to valley heights computed from the date in the upper graph, by comparison of each peak or valley (of a height greater than 0.001 in.) with the corresponding position for the preceding peak or valley, the difference (without regard to sign) being the peak to valley height.

Examination of the traces indicates that the packages (FIGS. 1 and 5) wound at the outside ratios, of 1.08 and 1.16 respectively, fall outside the criteria for the ridge-free yarn package of the invention, patterning due to wind ratio leading to the presence of ridges greater than 4 thousandths of an inch in peak-to-valley height. The three other packages, however, are uniformly smooth and ridge-free; and consequently, for this denier of yarn and under these winding conditions, a constant wind ratio of l.l2 is indicated, as wind ratio can be controlled at this value to an accuracy which will ensure that the patterning which begins to appear at the ratios of 1.08 and 1.16 is not encountered.

EXAMPLE 1 The process is carried out on a drawtwister operating at constant yarn delivery speed, under which conditions allowance needs to be made for the decrease in balloon tension during the winding period, in order that an excessive ratio, from the point of view both of yarn properties and of process operation, of initial to final balloon tension is avoided. The limiting ratio of balloon tensions will be dependent on the use to which the yarn is to be put, some uses, e.g., woven dress fabric, being more critical in regard to retraction differences, than others.

Hence, in the following process conditions, allowance is made for two values of initial to final balloon' tension ratio, B, namely 2.1 and 4.0; and one value, 1.18, of wind ratio. Winding ceased when, due to the increase in package radius during winding, the balloon tension had decreased to a value such that the above final balloon tension ratios obtained.

EXAMPLE 2 The process is carried out on a drawtwister operating at a yarn delivery speed that is varied in a manner to compensate for changes in package radius. In this instance, a value of B can be chosen which is typical of drawtwist processes operating at constant spindle speed; for instance, B can be 2.1.

With wind ratio again at 1.18 and with constant traveller speed of 5,200 r.p.m. and constant spindle speed of 11,340 r.p.m., the yarn delivery speed was varied from an initial 2,965 feet/min. to a final 6,160 feet/min. In this case, the bobbin diameter was 1.85 in.; and winding ceased at a package diameter of 3.85 in.

Although a constant spindle speed was employed in this case, it is, of course, possible to employ combinations of variable yarn delivery speed and variable spindle speed, the former being controlled in a manner so as to keep the wind ratio constant at the selected value and the latter programmed in a desired manner; or vice versa.

It is also possible according to the conditions of Example l to programme the spindle speed, as well as to control it for the purposes of maintaining constant wind ratio. Thus, for instance, it is possible to modulate or scramble the spindle speed at a relatively high frequency compared with the slow variation at which the spindle speed is controlled to maintain constant wind ratio with increasing package radius.

Further, or in addition, it is possible to programme the spindle speed so as abruptly to increase it and quickly traverse a particularly sensitive region for patterning, for instance that occurring close to a wind ratio of 1.

Yet another means whereby an excessive balloon tension ratio may be avoided is by increasing the drag on the traveller progressively during the wind.

The invention has been described particularly by reference to winding nylon yarn on a drawtwister, but it should be understood that it is applicable to all forms of over-end winding of yarns of any materials, but particularly the monofilament and multifilament yarns of synthetic polymer materials.

What is claimed is:

1. A process for producing a yarn package substantially free from ridges comprising winding the yarn into a package by means of a ring and traveller and spindle assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay according to one or more values of at least substantially constant wind ratio calculated to avoid regions of patterning in the package and main- Proccss Bobbin No. Diameter 'l'rarcllcr Speed (r.p.m.) Spindle Speed (r, Yum (inches) Initial Final Final Initial Final Final S d (B==2.l (8:40) (B=2.l 8:40) leet/ min.

1 ms 5.200 4.070 3.22:0 I 1.340 8,890 7.150 2.9240 2 2.. I 5,200 4.060 3.2245 11.340 3.880 7.160 4,030

In process No. l, the weight of yarn wound at the two values of B, and with a 15 inch overall length of build in the package, was 0.65 lb. and 1.56 lb'. and in Process No. 2, the weight of yarn was 1.2 lb. and 2.88 lb.

taining the wind ratio programme at least during a part of the winding, said wind ratio being obtained by continuously monitoring traveller speed, deriving an electrical signal from said monitored traveller speed, and

regulating a parameter of said process by means of said electrical signals.

2. A process as in claim 1 wherein the regulating step includes continuously varying the spindle speed throughout winding.

3. A process for producing a yarn package substan tially free from ridges comprising winding the yarn into a package by means of a ring and traveller and spindle assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay according to one or more values of at least substantially constant wind ratio calculated to avoid regions of patterning in the package and maintachometer. 

1. A process for producing a yarn package substantially free from ridges comprising winding the yarn into a package by means of a ring and traveller and spindle assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay according to one or more values of at least substantially constant wind ratio calculated to avoid regions of patterning in the package and maintaining the wind ratio programme at least during a part of the winding, said wind ratio being obtained by continuously monitoring traveller speed, deriving an electrical signal from said monitored traveller speed, and regulating a parameter of said process by means of said electrical signals.
 1. A process for producing a yarn package substantially free from ridges comprising winding the yarn into a package by means of a ring and traveller and spindle assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay according to one or more values of at least substantially constant wind ratio calculated to avoid regions of patterning in the package and maintaining the wind ratio programme at least during a part of the winding, said wind ratio being obtained by continuously monitoring traveller speed, deriving an electrical signal from said monitored traveller speed, and regulating a parameter of said process by means of said electrical signals.
 2. A process as in claim 1 wherein the regulating step includes continuously varying the spindle speed throughout winding.
 3. A process for producing a yarn package substantially free from ridges comprising winding the yarn into a package by means of a ring and traveller and spindle assembly with ring tilt of which the wave amplitude is greater than the traverse increment per revolution of the point of lay according to one or more values of at least substantially constant wind ratio calculated to avoid regions of patterning in the package and maintaining the wind ratio programme at least during a part of the winding, control over the maintenance of constant wind ratio being exercised electronically in a closed loop by electrical signals derived from the traveller and spindle respectively.
 4. A process according to claim 3 in which said electrical signals derived from the traveller emanate from a magnetic pick-up on the ring. 